How to change output in FOR Loop

Hello All,

I am in need of assisstance as my lecturer doesn't seem to know how to do what I want.

So, I need to create a loop that will change the output variable depending on the loop iteration. Sounds confusing so I'll put the code in and how I imagine it works. Apologies if it isnt actually possible but Ive been told it should be, just she doesnt know how to do it herself !

JanL = find(DateVector(:,2) == 1)';
FebL = find(DateVector(:,2) == 2)';
MarL = find(DateVector(:,2) == 3)';
AprL = find(DateVector(:,2) == 4)';
MayL = find(DateVector(:,2) == 5)';
JunL = find(DateVector(:,2) == 6)';
JulL = find(DateVector(:,2) == 7)';
AugL = find(DateVector(:,2) == 8)';
SepL = find(DateVector(:,2) == 9)';
OctL = find(DateVector(:,2) == 10)';
NovL = find(DateVector(:,2) == 11)';
DecL = find(DateVector(:,2) == 12)';

This what I have currently and want to shrink it into a loop. In my mind it works something like this:

X = [JanL FebL MarL AprL MayL JunL JulL AugL SepL OctL NovL DecL]
for k = 1:1:12
    X(k) = find(DateVector(:,2) == y)';
end 

Therefore producing the variable JanL with the datevector data accordingly. Doesnt work and I have no ideas how to do this after some substantial looking and investigating.

Any help much appreciated Thanks

[Walter Roberson]

http://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

Answer 1

[KSSV]

X = zeros(12,1) ; 
for k = 1:1:12
    X(k) = find(DateVector(:,2) == k)';
end 

The above is fine enough. You should go by indexing. X(1) means Jan, X(2) means Feb and so on....X(end) or X(12) means Dec. Read about indexing.

[Finley Watson]

Thanks, when I run this however, it states:

'Unable to perform assignment because the left and right sides have a different number of elements.'

What have I done wrong here?

Sorry, thanks

[KSSV]

You need to initialize the array X. Edited the answer.

[Finley Watson]

Done that as the X array contains what I need as variables, see 'JanL' etc. But it now sees JanL as an unrecognised function or variable.

[KSSV]

You need not to use string janL....your value for janL is nothing but X(1). Go by indexing, not by string.

Answer 2

[Jan]

Creating variables dynamically has a lot of severe disadvantaged. Using a struct is nicer, safer and more efficient.

X = {'JanL', 'FebL', 'MarL', 'AprL', 'MayL', 'JunL', ...
     'JulL', 'AugL', 'SepL', 'OctL', 'NovL', 'DecL'};
Data = struct();
for k = 1:1:12
    Data.(X{k}) = find(DateVector(:,2) == y)';
end

By the way, all of the variables end with L. Is this really useful? Maybe it is better to read, if you call the struct "L" and the fields "Jan", "Feb", ...